Although VHDL and FPGA tools often are very expensive, it is easy to get access to state-of-the-art software for free if you are a student. There are a number of simulators, editors and IDEs for working with VHDL. This article shows you how to install two of the most popular programs used by VHDL engineers.
Mentor Graphics’s ModelSim is the most common VHDL simulator out there, and chances are that you will have to use either ModelSim or the QuestaSim flavor of the program in your first VHDL job. It’s good design practice to make your code as portable as possible, and the code in this blog is no exception to that. Should you have access to another VHDL simulator, just go ahead and use it, it should work similarly.
Licenses for VHDL simulators are very costly, but luckily Mentor Graphics offers a student license of the ModelSim VHDL simulator. The student edition is limited to Microsoft Windows, and therefore I will also be using Windows for my tutorial series, although I am normally a Linux user.
If you are a student, you can request a free license at the Mentor Graphics website. Of course you have to read the terms and conditions to see if you qualify, and if you do, any email address will work.
This is a screencast of the licence request and installation process at the time of writing:
There is a bug in ModelSim Student Edition 10.4a which will appear if you install it into a directory path containing a whitespace. When you try to simulate, you may encounter the could not find interpreter “ScintillaTk” error message.
This happens if you for example install ModelSim to a directory containing a space, for example “Program Files”. The solution is simply to install ModelSim into the default directory suggested by the installer (C:\Modeltech_pe_edu_10.4a).
You can write code directly in the built-in editor in ModelSim, but you are better off using an external editor. For my tutorial series I will use Notepad++ which is a good, free alternative for Windows. It also has a VHDL plugin for syntax highlighting.
This is a screencast of how to download and install the editor and VHDL plugin:
When you have successfully installed ModelSim and Notepad++, you have everything you need to start learning VHDL!
Perhaps you are thinking: “What about hardware? Don’t I need an FPGA development board or something?”. Eventually you will want to try out your code on real hardware, but for the sole purpose of learning VHDL, a simulator is all you need.